A 2.4 GHz CMOS class-F power amplifier with reconfigurable load-impedance matching

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A novel reconfigurable CMOS class-F power amplifier (PA) at 2.4 GHz is proposed in this paper. It is able to match the output load variations mainly due to the effect of hand and head on a mobile phone. The effect of load variation on power-added efficiency (PAE), output power, and distortion is compensated by reconfiguring the output network using an impedance tuner. The tuner controls the output matching at fundamental frequency without affecting the class-F harmonic tuning up to 3rd harmonic. To the best of our knowledge, this is the first design of a CMOS class-F PA addressed to compensate the effect of load variation. Measurement results for 50 ohm load impedance show a maximum PAE of 26% and maximum output power of 19.2 dBm. The measured total harmonic distortion is 4.9%. Measurement results for load values other than 50 ohm show that PAE increases from 6.5% (not-tuned PA) up to 19.9% (tuned PA) with the same output power (19.2 dBm). Tuning also reduces the adjacent-channel leakage ratio by 5 dB and the spectral regrowth of a Wi-Fi signal at the PA output. The size of the fabricated chip is 1.6 mm × 1.6 mm.Peer ReviewedPostprint (author's final draft

Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review

Advances in reflectarrays and array lenses with electronic beam-forming capabilities are enabling a host of new possibilities for these high-performance, low-cost antenna architectures. This paper reviews enabling technologies and topologies of reconfigurable reflectarray and array lens designs, and surveys a range of experimental implementations and achievements that have been made in this area in recent years. The paper describes the fundamental design approaches employed in realizing reconfigurable designs, and explores advanced capabilities of these nascent architectures, such as multi-band operation, polarization manipulation, frequency agility, and amplification. Finally, the paper concludes by discussing future challenges and possibilities for these antennas.Comment: 16 pages, 12 figure

Tunable Impedance Matching Network Fundamental Limits and Pracitical Considerations

As wireless devices continue to increase in utility while decreasing in dimension, design of the RF front-end becomes more complex. It is common for a single handheld device to operate on a plethora of frequency bands, utilize multiple antennae, and be subjected to a variety of environments. One complexity in particular which arises from these factors is that of impedance mismatch. Recently, tunable impedance matching networks have begun to be implemented to address this problem. ^ This dissertation presents the first in-depth study on the frequency tuning range of tunable impedance matching networks. Both the fundamental limitations of ideal networks as well as practical considerations for design and implementation are addressed. Specifically, distributed matching networks with a single tuning element are investigated for use with parallel resistor-capacitor and series resistor-inductor loads. ^ Analytical formulas are developed to directly calculate the frequency tuning range TR of ideal topologies. The theoretical limit of TR for these topologies is presented and discussed. Additional formulas are developed which address limitations in transmission line characteristic impedance and varactor range. Equations to predict loss due to varactor quality factor are demonstrated and the ability of parasitics to both increase and decrease TR are shown. Measured results exemplify i) the potential to develop matching networks with a small impact from parasitics, ii) the need for accurate knowledge of parasitics when designing near transition points in optimal parameters, iii) the importance of using a transmission line with the right characteristic impedance, and iv) the ability to achieve extremely low loss at the design frequency with a lossy varactor under the right conditions (measured loss of -0.07 dB). ^ In the area of application, tunable matching networks are designed and measured for mobile handset antennas, demonstrating up to a 3 dB improvement in power delivered to a planar inverted-F antenna and up to 4–5.6 dB improvement in power delivered to the iPhone™ antenna. Additionally, a single-varactor matching network is measured to achieve greater tuning range than a two-varactor matching network (\u3e 824–960 MHz versus 850–915 MHz) and yield higher power handling. Addressing miniaturization, an accurate model of metal loss in planar integrated inductors for low-loss substrates is developed and demonstrated. ^ Finally, immediate future research directions are suggested: i) expanding the topologies, tuning elements, and loads analyzed; ii) performing a deep study into parasitics; and iii) investigating power handling with various varactor technologies

Tunable decoupling and matching concepts for compact mobile terminal antennas

[no abstract

Study of quasi-optical circuit techniques in varactor multipliers

Quasi-optical circuit techniques in varactor multiplier

WIRELESS ANTENNA MULTIPLEXING USING TUNABLE ANTENNA FOR SPACE APPLICATIONS

Recent development in communication technologies shifts the communication paradigm from point to point to multi-user wireless systems. These developments eased the use of mobile telephone, satellite services, 5G cellular, smart application, and the Internet of Things. The proliferation of mobile devices has necessitated an elaborate mechanism to serve multiple users over a shared communication medium, and a multiplexing approach is introduced to serve this purpose. Multiplexing refers to a method that aims at combining multiple signals into one signal such that each user would be able to extract its desired data upon receiving the multiplexed signal. This spectrum sharing allows wireless operators to maximize the use of their spectrum to accommodate a large number of users over fewer channels. In Space applications, where sensors like temperature, attitude, IR, Magnetic, etc. send information using antennas operate at a different frequency, there is a need to collect all or some of these data using a single device. A wideband antenna requires a filtering process in order to remove unwanted signals that lead to a complex circuit design. Furthermore, the use of multiple antennas ends up with a larger size and additional complexity. Therefore, the tunable antenna is an excellent candidate which provides a perfect solution for such scenarios. A tunable antenna whose frequency characteristics shifted by applying tuning action can be used to operate as a multiplexing device that can collect signals from different surrounding antennas; each operates at a fixed frequency. A system architecture for wireless multiplexing using a tunable antenna is proposed in this project. An electronically tunable antenna using varactor diode as a tuning element is used as the multiplexing device that can collect signals from different surrounding antennas. The system consists of an RF front end and a control circuit/system for wireless multiplexing. The RF front end consists of a tunable antenna, tunable phase shifter, tunable bandpass filter, low noise amplifier, mixer, voltage-controlled oscillator, and an intermediate frequency filter. The control unit comprises a microcontroller, DAC, CMOS oscillator, power module, and a USB interface for communication with custom-built software installed on a PC. The device has functions for control, digital signal processing, and de-multiplexing. The device is fed with an input multiplexed signal, and the de-multiplexed output signals are extracted and displayed on the graphical user interface of the software. Due to the reconfigurability and programmability of the device, it presents a flexible, cost-effective solution for a variety of real-world applications

Study of a small solar probe /sunblazer/. part ii- spacecraft and payload design progress report, jul. 1, 1964 - jun. 30, 1965

Design considerations for Sunblazer solar probe and payloa

Design and Optimization of Broadband Matching Networks for Widely Steerable Phased Array Radar Systems

The use of phased arrays have become prevalent in radar systems for military and weather applications due to their planar configuration and ability of electronic steering. However, mutual coupling between surrounding antenna elements causes degradation in performance at wide scan angles and broad bandwidth. This mutual coupling creates impedance mismatches at the element-level. A matching network can be used to correct this, but broadband matching networks that consider scan angle have not been explored. This work introduces a novel optimization method for designing matching networks. This method seeks to improve performance for wide-scanning broadband phased arrays, especially NASA’s Ecological Synthetic Aperture Radar (EcoSAR). The fabricated static matching network achieves a 78% reduction in the optimizer objective function and provides a 10 dB match for the majority of the scanning range of -40° to 40° at a fractional bandwidth of 28.7%. This method is also used to design a tunable matching network that achieves a measured 99.95% reduction in the optimizer objective function and provides a 15 dB match across frequency and scanning range for the EcoSAR array using frequency bins. This novel design method shows great promise for improving performance for future wide-scanning broadband phased array systems

Microstrip Patch Electrically Steerable Parasitic Array Radiators

This dissertation explores the expansion of the Electrically Steerable Parasitic Array Radiator (ESPAR) technology to arrays using microstrip patch elements. Scanning arrays of two and three closely-coupled rectangular patch elements are presented, which incorporate no phase shifters. These arrays achieve directive radiation patterns and scanning of up to 26° with maintained impedance match. The scanning is effected by tunable reactive loads which are used to control the mutual coupling between the elements, as well as additional loads which compensate to maintain the appropriate resonant frequency. The design incorporates theoretical analysis of the system of coupled antennas with full-wave simulation. A prototype of the threeelement array at 1 GHz is fabricated and measured to exhibit a maximum gain of 7.4 dBi with an efficiency of 79.1%. Further, the microstrip ESPAR is thoroughly compared to uniformlyilluminated arrays of similar size. To satisfy the need for higher directivity antennas with inexpensive electronic scanning, the microstrip ESPAR is then integrated as a subarray. The three-element subcell fabrication is simplified to a single layer with an inverted-Y groove in the ground plane, allowing for DC biasing without the need for the radial biasing stubs or tuning stubs found in the two-layer design. The 1 GHz ESPAR array employs a corporate feed network consisting of a Wilkinson power divider with switchable delay line phase shifts, ring hybrid couplers, and achieves a gain of 12.1 dBi at boresight with ±20° scanning and low side lobes. This array successfully illustrates the cost savings associated with ESPAR subarray scanning and the associated reduction in required number of phase shifters in the RF front end